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Avalanche Advisory

Turnagain Area Avalanche Advisory
Forecaster:   John Fitzgerald  
Monday, March 17th 2014
Created: Mar 17th 6:30 am
3 Considerable Alpine / Above 2,500' Travel Advice: Dangerous avalanche conditions. Careful snowpack evaluation, cautious routefinding and conservative decision-making essential.
2 Moderate Treeline / 1,000'-2,500' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
2 Moderate Below Treeline / Below 1,000' Travel Advice: Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.
 Show the Complete North American Avalanche Danger Scale
The Bottom Line

The avalanche danger is MODERATE on slopes under 35 degrees, and most terrain below treeline.  

Above treeline, in wind loaded areas and on steep upper elevation slopes the avalanche danger is CONSIDERABLE.

The likelihood of triggering fresh wind slabs 12-18” in depth is on the high end of the scale today.

The likelihood of triggering a dangerous deep slab avalanche up to 5’ in depth is much lower.  However, the consequences of triggering a deep slab are high due to their potential size and volume.

An enjoyable day can be had on slopes under 35 degrees, away from the runout of large paths and by avoiding likely trigger points.


Primary Concern

A modest amount of new snow overnight and continuing into today will be easily blown around by the wind.  The most likely avalanche problem to encounter today will be freshly formed wind slabs on leeward slopes, in starting zones and in cross loaded gullies.  Slab depths will be in the 12-18” range.  

General wind direction will be out of the East and in the 30 to 40 mph range on ridge tops.  Keep in mind that wind direction will vary from place to place.  Rather than focus on the compass, it is more important to be able to recognize wind slabs by their look and feel.  They will appear rounded, smooth and pillowy.  They will feel “upside down” and hollow.  Shooting cracks, an obvious sign of unstable snow, commonly occur on newly formed wind slabs.

Avoiding terrain where wind slabs are present will be the best way to manage this problem today.


Secondary Concern

A layer of weak snow buried 2-5 feet deep is still taking time to adjust to the load it received last week (5’ snow/5” water).  This layer was the likely culprit in numerous large natural and human triggered avalanches over the weekend.  While time is helping to heal this wound, the destructive potential of an avalanche at this layer is significant.  This newest slab, a combination of the March 10th and March 14th storms, is thick enough in most places that it is difficult to impact the layer in question.  Because of this it will be possible to travel on steep terrain without any of the obvious signs, including avalanches, to show themselves.  It will also be possible for a slope to have a plethora of tracks on it before releasing.  Add in the fact that we have had avalanches triggered remotely and this problem becomes even more complex.

Check our observations page for recent avalanche activity and a powerful VIDEO of a snowmachine triggered deep slab avalanche just outside of the forecast area.

Rather than trying to outsmart this instability, it is better to negotiate this problem by avoiding steep slopes and likely trigger points altogether.  Likely trigger points include shallow spots in the snowpack and steep rollovers.


Mountain Weather

In the past 24 hours the mountains around Eastern Turnagain Arm have picked up 4-6” of new snow with .3” of water.  Ridgetop winds have averaged 15mph out of the East with a max gust of 47mph.  Temperatures have averaged 10 degrees F and are currently in the teens F.

Today expect lingering snow showers with another 2-3” of snow possible.  Temperatures at 1,000’ will warm into the high 20s/low 30s F.  Ridgetop winds will be out of the East in the 30 to 40 mph range.

The extended outlook is calling for an unsettled pattern to bring light snow amounts through Wednesday.  A clearing trend looks to develop later in the week.

This is a general backcountry avalanche advisory issued for Turnagain Arm with Turnagain Pass as the core advisory area (this advisory does not apply to highways, railroads, or operating ski areas).

Winter snowmachine use open/closed status and riding conditions updates

Riding status is not associated with avalanche danger. An area will be open to motorized use in accordance to the Forest Management Plan when snow coverage is adequate to protect underlying vegetation. Backcountry hazards including avalanche hazard are always present regardless of the open status of motorized use areas.

(Updated: Mar 15, 2017 )

AREA STATUS WEATHER AND RIDING CONDITIONS
Glacier District
Johnson Pass: OpenPlease park on road in and leave the turnaround (near outhouse) open for trailers to turn around.
Placer River: Open
Skookum Drainage: OpenSkookum drainage closes to motorized use on April 1 annually as per the Chugach National Forest Plan document.
Turnagain Pass: Open
Twentymile: Open
Seward District
Carter Lake: Open
Lost Lake Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Primrose Trail: OpenPlease STAY ON existing and hardened trail surface through the lower sections of this route.
Resurrection Pass Trail: ClosedClosed for 2016/17 winter season. This is a non-motorized season. This alternates every other year and will open again during the 2017/18 winter.
Snug Harbor: Open
South Fork Snow River Corridor: Open
Summit Lake: Open

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The information in this advisory is from the U.S. Forest Service, which is solely responsible for its content. This advisory describes general avalanche conditions and local variations always occur. This advisory provided by the Chugach National Forest, in partnership with Friends of the Chugach National Forest Avalanche Information Center.


USFS SNOW AND AVALANCHE HOTLINE (907) 754-2369
If you have comments or questions regarding CNFAIC operations or winter recreation management, please email staff@chugachavalanche.org
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